The role of REVOLUTA and KANADI1 in plant development and environmental responses

Abstract

In plants, the establishment of organ patterning and polarity is mediated by the action of several transcription factors. Among them, KANADIs and HD-ZIPIIIs act antagonistically by which they play crucial roles in organ polarity. Using a combination of chromatin immunoprecipitation (ChIP-Seq) approach and tiling arrays, we could identify a set of potential direct target genes of KAN1. Further analysis showed that a number of KAN1 targets appear to regulate organ patterning or response to auxin. In addition, KAN1 shares a set of common direct targets with REV, implying that the REV/KAN1 module acts in organ patterning through opposite regulation of shared targets. As sessile organisms, plants have to continuously adjust growth and development to changing environmental conditions. During the final stage of growth, plants induce leaf senescence to reallocate nutrients and energy-rich substances from mature leaves to reproductive seeds, leading to increased reproductive success. Therefore leaf senescence is tightly coupled to the developmental age of the plant. In this study, we show that class III HD-ZIP transcription factors have an additional role in controlling the onset of leaf senescence in Arabidopsis. We report that acting as a redox-sensitive transcription factor, REV directly and positively regulates the expression of WRKY53, a senescence-related transcription factor. REV is required for the induction of WRKY53 in response to oxidative stress, and reducing the activity of HD-ZIP III genes strongly delays the onset of leaf senescence. Besides WRKY53, we also identified nine direct REV targets which are differentially expressed during senescence. Thus, a crosstalk between early and late stages of leaf development appears to contribute to reproductive success.